Compensators Concentrate Radiation to Kill Cancer

This could not be done on any other machine. By combining G-code programming with the ability for a Windows-based file to communicate directly with a machine tools source code for automation and production routines, .decimal, Inc. (Sanford, FL) automatically sets up, generates tool paths and part programs, simulates, confirms, cuts, and performs in-process measurement from files it receives via email. The results could save your life.

.decimal (pronounced dot-decimal) makes compensators, essentially 3D filters made from aluminum or brass that attach to a radiation treatment machine and concentrate radiation specifically on cancerous tissue, saving as much surrounding tissue or bone as possible. The idea came from company founder Richard Sweats expertise and experience in radiation therapy, including calculating radiation dosages on various types of equipment for patients. At the hospital, I was the liaison between our hospital and the local machine shops making various parts for our machines, he relates. I was having issues with many of our machine shops and decided I could do it better.

Very few people were looking at the idea of compensators for radiation equipment in the late 1990s, according to Sweat. Those that did made them with students on desktop machines with poor manufacturing practices. The result was very poorly manufactured compensators that were not very accurate when the need for accuracy around a tumor must be absolute.

By comparison, each .decimal compensator is machined to tolerances as close as 0.010 in precise dimensions unique to each patient. Because they are made directly from 3D digital scans of tumor areas received by SRP via email, Sweats name for his patent-pending compensators is .decimal (which stands for digitally enhanced compensation/intensity modulation with alloys).

The .decimal process begins with the file of the patients tumor area made from a 3D scan, says Sweat. This file is emailed to us. With our software, we read in the complex 3D surface along with all the patient specific statistics and automatically confirm the receipt of the data back to the hospital that sent it.

Custom CAM software selects the correct blank from a set of blank diameters and thickness based on the prescribed dosage and 3D configuration required. Sweats company machines the compensators on any of nine Nexus vertical machining centers from Mazak (Florence, KY) in addition to a Variaxis 500/5 five-axis machining center. Different machines are used for different fixture arrangements governed by blank size and radiation beam divergence requirements, Sweat explains.

Mazak wrote custom displays for the .decimal products that essentially apply Sweats business logic to the machining process. Customer and patient identification is everything. Once the operator brings up the custom display to load the fixture, the Mazatrol Fusion 640 control graphically walks him through loading and processing each part.

For example, blank diameters can vary from 3.5 inches up to 12 inches, and thicknesses from 1 to 2 inches. A series of checks verifies the appropriate part was loaded, and a touch probe confirms the zero location on each subplate, then the proper EIA program is recalled. After the operator enters all setup data, the custom application confirms that all constraints are met and all files are found. Then its a matter of closing the door and pressing Cycle Start.

By comparison, other compensator providers mill a piece of foam and cast the compensator with an alloy of molten lead that, when cooled, leaves a filter filled with voids and porosities. These other methods leave all the in-process inspection up to x-ray verification for accuracy. Thus, one may not know of a manufacturing error until the casts already been poured and set, In addition, by requiring multiple set-ups on various different machines and fixturing devices, tolerance errors accumulate, and the result is a less-accurate representation of the radiation pattern needed to address the tumor.

The Mazak routine not only allows .decimal to touch off each part prior to machining to confirm the correct setup, the probe is used for automated inspection during cutting. Each part is probed individually, each part is cut individually, and inspection and cutting results are logged with each job and saved to .decimals database. The concept was for a doctor to order an MRI and email the file to SRP, then have an automated process full-circle. Sweat confirms, Our process can go from receiving a patients 3D configuration to shipping a finished machine filter in three hours. Because there is only one setup on each Nexus milling machine, .decimals CpK on each Nexus machining center is between 2.0 and 3.4. Currently, .decimal has attained both ISO 9001:2000 and ISO 14001 certifications along with complying with all federal regulations for contract medical device manufacturers.

.decimal also takes advantage of Mazak Cyber Monitoring technology to run a third shift lights out without sacrificing any production time or part accuracy. Communications and control is always maintained over the entire manufacturing process.

Radiation machines themselves can run into millions of dollars to acquire. Compensators provide very cost-effective means of delivering higher doses of radiation to tumors while minimizing dose to surrounding tissues. In smaller clinics or developing countries that get by with 10 or 20-year-old machines, compensators give these providers a more precise and improved form of radiation therapy for their patients.

Networking, automation, and advanced machining capabilities all contribute to Sweats vision of ultimately reproducing SRP in other locations. Theres great opportunity for this process here and overseas, where they may not have the latest and greatest and thus most expensive technology he says.  Here in America, we tend to throw so much money at very expensive and complex electronically controlled radiation therapy technologies. Our hope is to partner with shops in cities around the world that have or will buy Mazak machine tools to franchise our process of producing compensators. We would take the orders here in the U.S., generate the tool paths, and send them the part programs. Then they would have an automated process for their respective location without the time delays associated with international shipping, customs, and local tariffs.

The ability to network, both LAN and WAN, thereby enabling us to send the toolpath information to the machine ties it all together, he continues. No one else had this capability. Mazak was extremely helpful in helping us make the .decimal concept work as we envisioned it. The goal of radiation oncology is to deliver as much dose as possible to the tumor volume without damaging normal structures. Combining the .decimal process with the Nexus machining center creates a big step forward in achieving it.